Run results for: isArray vs instanceof vs Symbol.iterator vs Object.prototype.toString.call

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36

Browser: Chrome 85

Operating system: Mac OS X 10.15.6

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
isArray	257789.8 Ops/sec
instanceof	246575.7 Ops/sec
Symbol.iterator	153301.6 Ops/sec
Object.prototype.toString.call	217297.6 Ops/sec

Script Preparation code:

var types = {
  array: [1,2,3],
  number: 123,
  string: '123',
  map: new Map([[1,1],[2,2],[3,3]]),
  set: new Set([1,2,3]),
  buffer: new ArrayBuffer([1,2,3]),
  boolean: true,
  arrow: () => {},
  function: function () {},
  object: {},
  u8: new Uint8Array(),
  u16: new Uint16Array(),
  u32: new Uint32Array(),
  i8: new Int8Array(),
  i16: new Int16Array(),
  i32: new Int32Array()
}

var keys = Object.keys(types)

Tests:

isArray
keys.map(key => Array.isArray(types[key]) === true)
instanceof
keys.map(key => (types[key] instanceof Array) === true)
Symbol.iterator
keys.map(key => types[key][Symbol.iterator] !== undefined)
Object.prototype.toString.call
keys.map(key => Object.prototype.toString.call(types[key]) === '[object Array]')

Run results for: isArray vs instanceof vs Symbol.iterator vs Object.prototype.toString.call

Symbol.iterator also matches TypedArray, Map, and such

isArray

instanceof

Symbol.iterator

Object.prototype.toString.call